Computational modeling of river hydrodynamics and ecology

目前关于从河流分配水的决定受到维持河流或溪流中有生存能力的生态系统的要求的制约。目前的做法是利用自然栖息地作为生态的替代品，其基础是假设如果物理条件与现有水生种群使用的条件相似，则生态将得到维持。需要可靠的水动力模拟工具来预测作为水流流量和几何形状函数的详细深度、速度和温度分布。 在这项探索基金申请中提出的研究将由三个具体项目组成，这些项目将导致水生生态建模方面的重大改进。第一个项目是开发一种新的方法来处理建模中的水动力部分，从而使不同维度分辨率的模型同时耦合和求解。一个例子是对河流的大部分长度使用一维(纵向)模型，但在少数选定地点使用扩展的二维(水平面)模型。类似地，二维模型还可以包含在所有三个维度上建模的区域。第二个项目涉及由于水面变化和航道水深测量而进入和离开航道冲积基质的近地表地下水流动。由于基质内的流动比表面慢得多，当水返回到水流中时，它可能具有显著不同的性质(例如温度和溶解氧)。这对鱼类的产卵和孵化很重要。第三个研究项目是对一种全新的方法的贡献，该方法通过尝试直接预测物种种群的空间分布来模拟溪流的生态。这项研究将与生物学家和数学家合作，他们将开发控制偏微分方程式。这些方程在形式上类似于流体动力学方程，我们的研究将是适应和/或开发有效和高效的数值求解方法。这项研究有可能改变我们理解水生生态系统的方式，并提供合理的河流径流建议。

Current decisions concerning water allocation from rivers are constrained by the requirement of maintaining a viable ecosystem in the river or stream. The current practice is to use physical habitat as a surrogate for ecology based on the assumption that if the physical conditions are similar to those used by existing aquatic populations then the ecology will be maintained. Reliable hydrodynamic modeling tools are required to predict detailed depth, velocity and temperature distributions as a function of the stream discharge and geometry. The research proposed in this Discovery Grant application will be comprised of three specific projects that will lead to significant improvements in aquatic ecology modeling. The first project is the development of a new approach to the hydrodynamic component of the modeling whereby models of different dimensional resolution are coupled and solved simultaneously. An example is using a one-dimensional (longitudinal) model for the majority of the length of a river but with an expanded two-dimensional (horizontal plane) model at a few selected sites. Similarly, the two-dimensional model may also contain regions which are modeled in all three dimensions. The second project concerns near surface groundwater flow that enters and leaves the alluvial substrate of the channel due to water surface variations and channel bathymetry. As flow within the substrate is much slower than on the surface, the water may have significantly different properties (e.g. temperature and dissolved oxygen) when it returns to the stream. This is important for fish spawning and incubation. The third research project is a contribution toward an entirelynew approach that models the ecologyof the stream by attempting to directlypredict the spatial distribution of species populations. This research will be in collaboration with biologists and mathematicians who will develop the governing partial differential equations. These equations are similar in form to the hydrodynamic equations and our research will be to adapt and/or develop effective and efficient numerical solution methods. This research has the potential to change the way we understand aquatic ecosystems and provide reasonable instream flow recommendations.